However, the TravellerMap site is a map of the Traveller galaxy, not the real Milky Way, so I had to pull out the image editor and build it from scratch. This is based on the Traveller galaxy map first introduced to the site back in 2005, courtesy of Clifford Linehan from his (now defunct?) Zhodani Core Route site, sourced by Marc Miller:

There are definite differences between the real and fictional galaxy. For example, in the real Milky Way, Earth's sun is part of the Orion Arm, which is mere spur off of the Perseus Arm, next to the Sagittarius Arm. In the Traveller galaxy, Terra appears to be in the main body of a major arm. The real Milky Way is a distinctive barred spiral, whereas the Traveller galaxy is not notably barred (although I rendered a subtle bar in anyway). In a real galaxy, there are nearly as many stars in the rifts between arms as there are in the arms themselves - the arms are slowly propagating gas density waves that induce more star formation, so they are full of bright young stars. In the Traveller galaxy, the rifts have much lower density, which makes things trickier for the Zhodani core expeditions. I don't have a problem with this difference - after all, space in Traveller is 2D. I view this as a perfectly acceptable simplification for the game universe, and don't attempt to fit it to reality. To me, it's a lot like chess. Real battles between opposing armies rarely take place on a perfectly flat 8x8 grid, but that doesn't mean chess isn't a fun game that teaches real strategy.

To create the image I took the galaxy map (isolated to a white-on-black mask), the pseudorandom stars from the map site, Paint.NET and experimented with various layers, blurs, and mixing functions. The cloudy arms were created by blurring the map, rendering in clouds, then using a twist filter. This had various densities of galactic structure and stars layered on top. The core was generated with several overlapping gradients to get an overall white glow, the rosy core, and the bright bar.

If you zoom in, the "Galaxy" image will gradually fade to the "Nebula" background used for candy-style rendering (c/o Wayne Peters). The only really grody bit is that the local rifts fade in as well, and they have abrupt edges. I'm pondering what to do there. Classic Library Data states:

Situated in the center of the Imperium, Capital's astrographic location has proven of prime importance, as it controls the only gap in the Rifts for thousands of parsecs. Besides being a communications hub, Capital is a cultural center, and educational focus. - Adventure 3: Twilight's Peak (emphasis mine)

The emphasized portion is not present in Supplement 8: Library Data (A-M) and later updates of the Library Data for Capital, possibly because the Traveller universe was more refined. However, looked at on the scale of hundreds of parsecs, it is true that the Imperium - centered on Capital, does control the only large gap in the rifts... if the Great Rift and Lesser Rift are presumed to continue on for a thousand parsecs in each direction.